The present disclosure is directed to an indicator for restricted fluid flow. More specifically, the present disclosure is directed to a visible indicator for a filter system that provides a signal when fluid flow through a filter is undesirably restricted.
Many systems include a filtered fluid intake in order to operate, and an example of such a system is an internal combustion engine. The internal combustion engine includes a filtered air intake that supplies filtered air for combustion to the cylinders. The filter can become clogged or restricted with particulates. Subsequently, airflow to the cylinders becomes restricted, which can negatively impact the performance of the engine. These performance degradations are not always immediately noticeable to the user. Taking a filter assembly apart to inspect it is often tedious. Also, a user often is not able to visually determine whether the filter is sufficiently clogged to create degradation in performance. According, there is a need for a device to indicate when a fluid filter is undesirably restricted.
Several types of indicators for restricted fluid flow are known. Some devices are relatively expensive real-time pressure indicators. Often these real-time pressure indicators reset themselves when the engine is turned off and there is no flow of air in the intake. These devices are useful when the user of the engines monitors the condition of the engine while the engine is turned on. But such indicators do not provide an indication to a service person that is maintaining or repairing the engine when the engine is turned off.
One device directed to providing a visual indication of restricted air low even after a compressor is turned off is described in U.S. Pat. No. 5,616,157. The device includes a movable ball separating two chambers. A first chamber is in communication with the filtered airflow, and a second chamber is in communication with the ambient atmosphere. As pressure drops in the first chamber as a result of a restricted airflow, the ball is drawn into the first chamber. After the ball has moved a threshold amount, the ball releases an indicator flag that remains released after the compressor has been turned off or restarted.
There is a continuing need, however, to provide a relatively inexpensive, responsive, and accurate indicator for restricted fluid flow that maintains the alert after the fluid flow has stopped.